Discharge printing agent, container, ink-jet recording apparatus, method for discharge printing, method for forming image, and method for stabilizing discharge printing agent

ABSTRACT

The present invention provides a discharge printing agent containing thiourea dioxide, wherein the discharge printing agent further contains at least one of the following components (i) and (ii): (i) at least one salt selected from the group consisting of a salt of monocarboxylic acid, a salt of ascorbic acid, and a salt of metasilicic acid; and (ii) β-diketone.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Japanese Patent Application Nos.2013-66066, 2013-66067, and 2013-66068 filed on Mar. 27, 2013. Theentire subject matter of the Japanese Patent Application is incorporatedherein by reference.

The present invention relates to a discharge printing agent, acontainer, an ink-jet recording apparatus, a method for dischargeprinting, a method for forming an image, and a method for stabilizing adischarge printing agent.

BACKGROUND

As a discharge printing agent for use in discharge printing of fabric, adischarge printing agent containing, as a reductant, rongalite has beenknown. According to this discharge printing agent, fabric is subjectedto discharge printing by an oxidation-reduction reaction, and a colorimage may be formed on deep-color fabric by forming an image on a partwhich has been subjected to discharge printing.

However, since the reducing ability of the above-mentioned dischargeprinting agent containing rongalite is impaired within one day, forexample, it is necessary to use the discharge printing agent within ashort period of time after preparation. Moreover, the discharge printingability of the above-mentioned discharge printing agent containingrongalite is poor. Therefore, in some cases, even if a color ink isused, an appropriate image is not formed on the pan which has beensubjected to discharge printing.

SUMMARY

The discharge printing agent is a discharge printing agent comprisingthiourea dioxide, wherein the discharge printing agent further comprisesat least one of the following components (i) and (ii): (i) at least onesalt selected from the group consisting of a salt of monocarboxylicacid, a salt of ascorbic acid, and a salt of metasilicic acid; and (ii)β-diketone.

The container comprises the above-described discharge printing agent.

The ink-jet recording apparatus is an ink-jet recording apparatuscomprising a liquid ejecting unit of ejecting a liquid, wherein theapparatus further comprises a unit of applying the above-describeddischarge printing agent.

The method for discharge printing is a method for discharge printing offabric, the method comprising: a discharge printing agent-applying stepof applying the above-described discharge printing agent to fabric; anda heating step of heating a discharge printing agent-applied part.

The method for forming an image is a method for forming an image onfabric, the method comprising: a discharge printing step of subjectingfabric to discharge printing; and an image printing step of printing animage on a discharge printing-subjected part with an ink, wherein thedischarge printing step is performed by the above-described method fordischarge printing.

The method for stabilizing a discharge printing agent is a method forstabilizing a discharge printing agent that comprises thiourea dioxide,the method comprising adding at least one of the following components(i) and (ii) to the discharge printing agent, (i) at least one saltselected from the group consisting of a salt of monocarboxylic acid, asalt of ascorbic acid, and a salt of metasilicic acid, (ii) β-diketone.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are figures each showing an example of applying adischarge printing agent in the method for discharge printing.

FIG. 2 is a schematic view showing an example of a configuration of anink-jet recording apparatus.

FIG. 3 is a front view showing an example of a configuration of anink-jet printer of the ink-jet recording apparatus.

FIG. 4A is a plan view showing the state where fabric is set to a platenof the ink-jet recording apparatus. FIG. 4B is a cross-sectional viewtaken along line A-A of FIG. 4A.

FIG. 5 is a block diagram showing a configuration of the ink-jetrecording apparatus.

FIG. 6 is a function block diagram of the ink-jet recording apparatus.

DETAILED DESCRIPTION

The discharge printing agent is used for discharge printing of fabric.Examples of the fabric include clothes such as a T-shirt, a bathingsuit, and a sweat shirt; a bag; shoes; slippers; socks; furniture suchas a sofa; and a fabric good such as a flag. The fabric encompasses bothof a woven fabric and a non-woven fabric. From the view point of aneffect of discharge printing, a material of the fabric is, for example,a natural fiber. Examples of the natural fiber include cotton and silk.The material of the fabric may be a blended fabric obtained by mixingplural kinds of the fibers. The “discharge printing” is different inprocess and object to be subjected to discharge printing from bleachingusually performed in the home and the like, for example. Specifically,the bleaching performed in the home and the like is performed byimmersing clothes in an agent and allowing the clothes to stand tochemically decompose stains themselves by an oxidation reaction or areduction reaction. In contrast, “discharge printing” is performed bydirectly acting on dye molecules staining fabric, specifically cottonfibers to chemically decompose the molecules. The processes of“discharge printing” include, for example, in addition to processes ofimmersing fabric in an agent and allowing the fabric to stand, a processof heating the fabric at 100° C. or more using a device such as a devicecalled a heat press in the presence of high-temperature steam. In thepresence of high-temperature steam such as mentioned above, for example,thiourea dioxide (aminoiminomethanesulfinic acid) which is a maincomponent is decomposed, resulting in generation of sulfoxylic acidhaving a reducing ability. Thus, the scheme of the chemical reaction ofacting this sulfoxylic acid on the dye molecules is assumed. Thismechanism, however, is merely an assumption, and the present inventionis not limited by this assumption.

As mentioned above, the discharge printing agent is a discharge printingagent comprising thiourea dioxide, wherein the discharge printing agentfurther comprises at least one of the following (i) and (ii): (i) atleast one salt selected from the group consisting of a salt ofmonocarboxylic acid, a salt of ascorbic acid, and a salt of metasilicicacid; and (ii) (3-diketone.

In the discharge printing agent, thiourea dioxide as a reductant and atleast one of the components (i) and (ii) are used in combination, sothat the discharge printing agent is capable of being stored for a longperiod of time, for example. Moreover, in the discharge printing agent,thiourea dioxide as a reductant and the component (i) are used incombination, so that the discharge printing ability is improved, forexample. In the discharge printing using thiourea dioxide, a reactionintermediate is stabilized by a nucleophilic reaction of carbonylcarbon, and the intermediate is decomposed over time, so that a yield ofeffective sulfoxylic acid is increased. Thus, it is assumed that adischarge printing effect is increased. This mechanism, however, ismerely an assumption, and the present invention is not limited by thisassumption. Moreover, the above-mentioned discharge printing agentcontaining rongalite has a problem in that formaldehyde is generated bydecomposition of the rongalite. Formaldehyde has a very strongirritating odor, and the irritating odor worsens the working environmentand causes an odor remaining in a product in some cases. It is thereforeconsidered that there is a case where generation of formaldehyde is notfavorable according to the working environment. In contrast, thedischarge printing agent does not require rongalite, so thatformaldehyde is not generated. Furthermore, according to the dischargeprinting agent, for example, it is possible to suppress corrosion of anink-jet head in an ink-jet recording apparatus when an ejection isperformed from the ink-jet head.

The amount of the thiourea dioxide to be added in the discharge printingagent is not particularly limited and is, for example, 0.5 wt % to 5 wt%, 1 wt % to 5 wt %. 2 wt % to 5 wt %, relative to the total amount ofthe discharge printing agent.

The salt of monocarboxylic acid is not particularly limited and is, forexample, at least one of a salt of formic acid, a salt of aliphaticcarboxylic acid, and a salt of an aliphatic carboxylic acid derivative.Examples of the salt of formic acid include sodium formate and potassiumformate. Examples of the salt of aliphatic carboxylic acid includesodium acetate, potassium acetate, sodium butyrate, and potassiumbutyrate. Examples of the salt of an aliphatic carboxylic acidderivative include sodium chloroacetate, potassium chloroacetate, sodiumglycolate, potassium glycolate, sodium pivalate (sodium trimethylate),and potassium pivalate (potassium trimethylate).

Examples of the salt of ascorbic acid include sodium ascorbate andpotassium ascorbate. There are an L-form and a D-form in ascorbic acid.Any of the L-form salt and the D-form salt may be used, or a mixture ofboth of them may be used.

Examples of the salt of metasilicic acid include sodium metasilicate andpotassium metasilicate.

As to the component (i), one kind may be used alone, or two or morekinds may be used in combination. The amount of the component (i) to beadded in the discharge printing agent is not particularly limited andis, for example, 0.5 wt % to 10 wt %, 2 wt % to 10 wt %, 2 wt % to 5 wt%, relative to the total amount of the discharge printing agent.

In the “β-diketone”, “ketone” encompasses all of carbonyl compounds(aldehyde, carboxylic acid, ester, and the like) and salts, ions, andhydrates thereof. The β-diketone is not particularly limited, andexamples thereof include acetylacetone, sodium malonate (monosodiummalonate, disodium malonate), potassium malonate (monopotassiummalonate, dipotassium malonate), 3-acetyl-γ-butyrolactone, dehydroaceticacid, and methyl acetoacetate, and the β-diketone is acetylacetone,disodium malonate, 3-acetyl-γ-butyrolactone, dehydroacetic acid, methylacetoacetate, or N-methyl acetoacetic acid amide.

One kind of the β-diketone may be used alone, or two or more kinds ofthe β-diketone may be used in combination. The amount of the β-diketoneto be added in the discharge printing agent is not particularly limitedand is, for example, 1 wt % to 15 wt %, 2 wt % to 15 wt %, relative tothe total amount of the discharge printing agent.

The discharge printing agent may further comprise acetone or an acetonederivative. The acetone derivative is, for example, a compoundrepresented by the following chemical formula where each of R₁ and R₂represents an alkyl group or hydrogen. The alkyl group is notparticularly limited and is, for example, an alkyl group with a carbonnumber of 1 to 20. The alkyl group may be, for example, a straight-chainalkyl group or a branched alkyl group. Specific examples of the alkylgroup include a methyl group, an ethyl group, a n-propyl group, anisopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group,a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, anoctyl group, a nonyl group, a decyl group, an undecyl group, a dodecylgroup, a tetradecyl group, a pentadecyl group, a hexadecyl group, aheptadecyl group, an octadecyl group, a nonadecyl group, and an icosylgroup. The compound represented by the following chemical formula is,for example, 2-hydroxy-2-methyl-4-pentanone. The amount of the acetoneor the acetone derivative to be added is not particularly limited andis, for example, 1 wt % to 10 wt %, for example, 2 wt % a to 10 wt %,relative to the total amount of the discharge printing agent.

The discharge printing agent may further comprise an amine base. Theamine base is, for example, primary amine and may have one amino groupor a plurality of amine groups. Examples of the primary amine includeaminoalcohol, a guanidine salt, a guanidine derivative, andN,N′-bis(2-aminoethyl)-1,2-ethanediamine. Specific examples of theaminoalcohol include 2-amino-2-hydroxymethyl-1,3-propanediol (AHP),2-amino-2-methyl-1-propanol (AMP). 2-amino-2-ethyl-1,3-propanediol(AEP), and 2-(2-aminoethoxy)ethanol (AEE). The guanidine salt is, forexample, guanidine carbonate, and the guanidine derivative is, forexample, aminoguanidine hemisulfate. The amount of the amine base (iii)to be added is not particularly limited and is, for example, 1 wt % to10 wt %, for example, 2 wt % to 10 wt %, relative to the total amount ofthe discharge printing agent. When the discharge printing agentcomprises the amine, the discharge printing agent may be stabilized fora long period of time even after one month (28 days) from preparation.

The discharge printing agent may further comprise water. The water is,for example, ion-exchange water or pure water. The amount of the waterto be added relative to the total amount of the discharge printing agentis, for example, the balance of the discharge printing agent, excludingother components.

The discharge printing agent may further comprise a water-solubleorganic solvent. As the water-soluble organic solvent, any ofconventionally known organic solvents may be used. Examples of thewater-soluble organic solvent include polyalcohol, a polyalcoholderivative, alcohol, amide, ketolcohol, ether, a nitrogen-containingsolvent, a sulfur-containing solvent, propylene carbonate, ethylenecarbonate, and 1,3-dimethyl-2-imidazolidinone. Examples of thepolyalcohol include glycerin (Gly), ethylene glycol, diethylene glycol(DEG), propylene glycol, butylene glycol, hexylene glycol,triethyleneglycol, polyethylene glycol, dipropylene glycol, tripropyleneglycol, polypropylene glycol, trimethylolpropane, 1,5-pentanediol, and1,2,6-hexanetriol. Examples of the polyalcohol derivative includeethylene glycol methyl ether, ethylene glycol ethyl ether, ethyleneglycol-n-propyl ether, ethylene glycol-n-butyl ether, diethylene glycolmethyl ether, diethylene glycol ethyl ether, diethylene glycol-n-propylether, diethylene glycol-n-butyl ether, diethylene glycol-n-hexyl ether,triethylene glycol methyl ether, triethylene glycol ethyl ether,triethylene glycol-n-propyl ether, triethylene glycol-n-butyl ether,propylene glycol methyl ether, propylene glycol ethyl ether, propyleneglycol-n-propyl ether, propylene glycol-n-butyl ether, dipropyleneglycol methyl ether, dipropylene glycol ethyl ether, dipropyleneglycol-n-propyl ether, dipropylene glycol-n-butyl ether, tripropyleneglycol methyl ether, tripropylene glycol ethyl ether, tripropyleneglycol-n-propyl ether, and tripropylene glycol-n-butyl ether. Examplesof the alcohol include methyl alcohol, ethyl alcohol, n-propyl alcohol,isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, isobutyl alcohol,ten-butyl alcohol, and benzyl alcohol. Examples of the amide includedimethylformamide and dimethylacetamide. The ketoalcohol is, forexample, diacetone alcohol. Examples of the ether includetetrahydrofuran and dioxane. Examples of the nitrogen-containing solventinclude pyrolidone, 2-pyrolidone, N-methyl-2-pyrolidone,cyclohexylpyrolidone, and triethanolamine. Examples of thenitrogen-containing solvent include thiodiethanol, thiodiglycol,thioglycerol, sulfolane, and dimethyl sulfoxide. The amount of thewater-soluble organic solvent to be added relative to the total amountof the discharge printing agent is, for example, 0.5 wt % to 30 wt %,for example, 5 wt % to 30 wt %, for example, 10 wt % to 20 wt %. Thewater-soluble organic solvents may be used alone or in a combination oftwo or more of them.

The water-soluble organic solvent is, for example, at least one of Glyand DEG which are high boiling point solvents and is, for example, Gly.The amount of the high boiling point solvent to be added relative to thetotal amount of the discharge printing agent is, for example, 0.5 wt %to 30 wt %, for example, 5 wt % to 30 wt %, for example, 10 wt % to 20wt %.

The discharge printing agent may further comprise conventionally knownadditives if necessary. Examples of the additives include a surfactant,a viscosity modifier, a surface tension regulator, an antioxidant, andan anti-mold agent. Examples of the viscosity modifier include polyvinylalcohol, cellulose, and a water-soluble resin.

The discharge printing agent may be prepared by mixing components otherthan the thiourea dioxide and at least one of the components (i) and(ii) in advance and then adding the thiourea dioxide and at least one ofthe components (i) and (ii) to the resultant mixture, for example.

The container is described below. The container is characterized incomprising the discharge printing agent. As a main body of thecontainer, for example, a conventionally known substance such as an inktank 20 in an ink-jet printer 1 shown in FIG. 3 described below may beused. For example, as a main body of the container, an ink cartridgehaving a case made of a resin or an ink pack formed of a flexible filmmay be used. If there is a concern that a function of discharge printingis reduced by a progress of a chemical reaction caused by impact givento the discharge printing agent at the time when the discharge printingagent is placed in a flexible ink pack, a container having a case may beused. In this instance, the discharge printing agent may be placeddirectly in the case. The discharge printing agent may be placed in aflexible ink pack arranged inside the case. Further, the dischargeprinting agent may be placed in a space between an ink pack formed of aflexible material and a wall of the case. Moreover, only a solid of thedischarge printing agent is placed in the container to mix with a liquidlater.

The ink-jet recording apparatus is described below. The ink-jetrecording apparatus is an ink-jet recording apparatus comprising aliquid ejecting unit of ejecting a liquid, wherein the apparatus furthercomprises a unit of applying a discharge printing agent. Examples of theliquid include an ink for ink-jet recording and a treatment liquid foruse in ink-jet recording. The ink-jet recording apparatus may furtherinclude a storage section of storing the container and may be configuredso that a liquid placed inside the container in the storage section isejected by the liquid ejecting unit. An apparatus having suchconfiguration is, for example, an apparatus having a configuration inwhich a unit of applying a discharge printing agent is added to theink-jet recording apparatus shown in FIG. 2 described below. Examples ofthe unit of applying a discharge printing agent include an ink-jet head,a spray, a stamp of applying a discharge printing agent to the fabric, abrush, and a roller. The present embodiment includes ink-jet heads 5shown in FIG. 3 as the unit of applying (ejecting) a discharge printingagent. The ink-jet recording apparatus may further comprise a dischargeprinting agent-storage section of storing a discharge printing agent.

The method for discharge printing is described below. The method fordischarge printing is a method for discharge printing of fabric, themethod comprising: a discharge printing agent-applying step of applyinga discharge printing agent to fabric; and a heating step of heating adischarge printing agent-applied part.

In the discharge printing agent-applying step, a discharge printingagent is applied by a method such as an ink-jet method of applying(ejecting) with an ink-jet head, a spray method, a stamp application, abrush application, or a roller application, for example. In the methodfor discharge printing, the discharge printing agent using the thioureadioxide and at least one of the components (i) and (ii) in combinationis used. Thus, corrosion of the ink-jet heads may be suppressed in thecase where the discharge printing agent is applied (ejected) by theink-jet method.

In the discharge printing agent-applying step, the discharge printingagent may be applied to the entire surface of fabric in which an imageis formed or a part of the surface. When the discharge printing agent isapplied to a part of the surface, a region mostly the same as at least apart to be subjected to printing with an ink(s) in the surface of fabricin which an image is formed is a discharge printing agent-applied part.When the discharge printing agent is applied to a part of the surface,the size of the discharge printing agent-applied part is bigger than thepart which is subjected to printing. For example, as shown in FIG. 1A,when a character (X) is printed on fabric (T-shirt in the presentexample) 100, the discharge printing agent is applied so that thedischarge printing agent-applied part 110 with a line width higher thanthe line width of the character is formed. Moreover, for example, asshown in FIG. 1B, when a pattern is printed on fabric (T-shirt) 100, thedischarge printing agent is applied so that a discharge printingagent-applied part 120 bigger than the pattern is formed.

The heating step is a step of heating a discharge printing agent-appliedpart. The heating may be performed using a commercially available iron,hot press apparatus, an oven, or a conveyor belt oven, for example. Whenthe iron or the hot press apparatus is used, for example, the dischargeprinting agent-applied part is heated in the state where a Teflon(registered trademark) sheet having a flat surface is placed on thepart. Thus, generation of a nap of the fabric may be suppressed, and forexample, when the method for discharge printing is used in the methodfor forming an image described below, an image may be printed smoothly.The heating temperature is not particularly limited and is, for example,in a range of 160° C. to 185° C. In the method for discharge printing,the discharge printing agent using the thiourea dioxide and at least oneof the components (i) and (ii) in combination is used. Thus, when thedischarge printing agent is used after being stored for a long period oftime, for example, after the elapse of one month, discharge printing offabric may be performed, and there is no generation of formaldehyde.

The method for forming an image is described below. The method forforming an image is a method for forming an image on fabric, the methodcomprising: a discharge printing step of subjecting fabric to dischargeprinting; and an image printing step of printing an image on a dischargeprinting-subjected part with an ink, wherein the discharge printing stepis performed by the method for discharge printing.

The method for forming an image may further comprise a step such as aheat-fixing step described below in addition to the above-mentioned twosteps, for example.

The discharge printing step is the same as described for the method fordischarge printing.

The image printing step is a step of printing an image on a dischargeprinting-subjected part or a discharge printing agent-applied part withan ink(s). When an image is printed on a discharge printingagent-applied part with an ink(s), the heating step in the method fordischarge printing may be performed after printing an image with anink(s). The ink(s) for use in the image printing step is notparticularly limited, and for example, a pigment ink, a dye ink, or thelike may be used, and a pigment ink is used.

The image printing step may be performed using an ink-jet recordingapparatus shown in FIG. 2. In the ink-jet recording apparatus of thepresent example, the image printing step is performed by an ink-jetmethod. As shown FIG. 2, this ink-jet recording apparatus is configuredso that an ink-jet printer 1 of printing a desired image by ejecting anink(s) on fabric and a printing control apparatus 70 of acquiring animage data of the desired image and controlling the ink-jet printer 1are connected via an interface.

The ink-jet printer 1 includes a frame-like frame 2 as shown in FIG. 3.The frame 2 includes a horizontal part 2 h located on the bottom part ofthe printer 1 and two vertical parts 2 v which are perpendicular to theboth ends of the horizontal part 2 h. In FIG. 3, identical parts tothose in FIG. 2 are denoted by identical reference numerals. The sameapplies to figures subsequent to FIG. 4.

A slide rail 3 horizontally supports and bridges the two vertical partsso that upper parts of the two vertical parts 2 v are linked with eachother. The slide rail 3 is provided with a carriage 4 so as to beslidable along the longitudinal direction (main scanning direction) ofthe slide rail 3. The lower surface of this carriage 4 is provided withfive piezoelectric ink-jet heads (liquid ejecting units) 5 arranged atpredetermined positions according to the respective colors in order toeject five color inks. The ink-jet printer 1 may be configured so thatit is provided with eight ink-jet heads, for example. Specifically, twohead units in each of which four ink-jet heads are disposed along adirection of moving the cartridge (hereinafter also referred to as“cartridge moving direction”) may be arranged so as to face thedirection orthogonal to the cartridge moving direction. In thisinstance, one head unit is provided with four ink-jet heads of ejectingthe respective four color inks (cyan, magenta, yellow, black), and theother head unit are provided with two ink-jet heads of ejecting a whiteink and two ink-jet heads of ejecting a discharge printing agent.

The respective upper parts of the two vertical parts 2 v are supportedby pulleys 6 and 7, and the pulley 6 is linked with a motor axis of amotor 8 supported by the vertical part 2 v. An endless belt 9 bridgesthe pulleys 6 and 7, and the carriage 4 is fixed at an appropriate partof this endless belt 9.

With such configuration, when the pulley 6 is rotated in the forwarddirection and the reverse direction by driving the motor 8, the carriage4 is driven to linearly reciprocate along the longitudinal direction(main scanning direction) of the slide rail 3. Thus, the ink-jet heads 5are reciprocated.

A mounting part 10 which detachably mounts ink tanks 20 is formed ineach of the two vertical parts 2 v. In one of the two mounting parts 10,two color ink tanks 20 may be inserted, and in the other mounting part10, three color ink tanks 20 may be inserted. Ink bags (not shown)formed in the inside of the respective ink tanks 20 are connected to therespective five sub tanks 30 located at the upper parts of the ink-jetheads 5 via flexible tubes 28. The five sub tanks 30 are communicatedwith the respective ink-jet heads 5 as described below, so that each inkis supplied from each ink tank 20 to each ink-jet head 5.

Slide mechanisms 11 are positioned on the horizontal part 2 h of theframe 2, and a platen (support) 12 is supported on the slide mechanisms11. This platen 12 is provided with a fixing frame (fixing unit) 15 sothat the position of the fabric is determined so as to face up a part tobe subjected to printing, and the fabric is set tightly and flatlywithout creases. The ink-jet printer 1 of the present example performsink-jet recording on a sewn T-shirt and however may be applied togeneral fabric. In the ink-jet printer 1 of the present example, thenumber of platens 12 is one, and however, the number of the platens isnot limited to one and may be increased as required. For example, whenan ink-jet printer having two platens is used, while an image isprinting on a T-shirt fixed on one of the platens, a T-shirt may befixed on the other platen. Thus, operating efficiency may be enhanced.

A platen convey mechanism (not shown) is arranged at a predeterminedposition of the ink-jet printer 1 in order to reciprocate the platen 12in a direction perpendicular to a sheet of FIG. 3 (which is a directionin which the slide mechanism 11 slides and a vertical scanning directionof the ink-jet printer 1). As the platen convey mechanism, a mechanismusing a rack, a pinion mechanism, and an endless belt may be applied,for example.

FIGS. 4A and 4B show the state where fabric is set to a platen. FIG. 4Ais a plan view, and FIG. 4B is a cross-sectional view taken along lineA-A of FIG. 4A. As shown in FIGS. 4A and 4B, the platen 12 has arectangular shape whose longitudinal direction is a direction orthogonalto the direction of reciprocating the carriage 4 in plan view and has asupporting surface 16 of supporting the T shirt 100. The lower surfaceof the platen 12 on the back side in a direction perpendicular to thesheet of FIG. 1B is connected to the slide mechanism 11 and a supportingmember 17 which are located so as to face the lower surface. Each of theupper parts of the both ends of the platen 12, parallel to thelongitudinal direction of the platen 12, has an arc shape.

The fixing frame 15 is configured so that a frame having L-shapedsections covers four sides of the supporting surface 16 of the platen12. An opening 15 a having an opening area slightly smaller than thearea of the supporting surface 16 is formed in a surface facing thesupporting surface 16 of the platen 12 in the fixing frame 15. The innersurface of the fixing frame 15, facing a side surface of the platen 12,is provided with an anti-slipping member 19 made of rubber. By providingthe inner surface with this anti-slipping member 19, the T-shirt 100 maybe set in the state where the T-shirt 100 is pulled in both of thelongitudinal direction (of the T-shirt) and the short direction (of theT-shirt) of the supporting surface 16 of the platen 12 at the time ofsetting the T-shirt 100 to the platen 12, and the T-shirt 100 may beheld without creases. When the T-shirt 100 is set to the platen 12, theT-shirt 100 is overlaid on the platen 12 from the hem side of theT-shirt 100 so as to cover the supporting surface 16 of the platen 12and is fixed with the fixing frame 15. The fixing frame 15 is providedso as to be rotatable by a rotating part (not shown) provided at the endpart of the platen 12 on the back side in a direction perpendicular tothe sheet of FIG. 4B. The T-shirt 100 is overlaid on the platen 12, andthereafter, the fixing frame 15 is rotated so as to fit in the platen12. Thus, the T-shirt 100 is fixed so as to be sandwiched between theplaten 12 and the fixing frame 15.

The ink-jet printer 1 includes a cover 13, and the cover 13 may protectthe ink-jet heads 5 and the slide mechanisms 11 by covering them. InFIG. 3, in order to specifically show the inside of the cover 13, thecover 13 is shown in perspective by drawing the cover 13 with a chaindouble-dashed line. An operation panel 14 including a liquid crystalpanel and an operation button is arranged at a predetermined position ofthe upper right part of the front surface of the cover 13.

The five ink-jet heads 5 shown in FIG. 3 correspond to the respectivefive color inks (white, yellow, magenta, cyan, and black), are arrangedin parallel along the direction of reciprocating the carriage 4, and arecommunicated with the respective ink tanks 20 via the respectiveflexible tubes 28 and the respective sub tanks 30. As a configuration ofsupplying the inks to the respective ink-jet heads, a conventionallyknown configuration may be used, for example (for example, see JP2004-291461 A).

By linking the ink tanks 20 with the respective sub tanks 30 via therespective flexible tubes 28, the inks in the respective ink tanks 20may be supplied to the respective sub tanks 30, and the ink tanks 20 maybe provided at the positions which are easily replaced. Thus, when theinks in the respective ink tanks 20 are run out, the ink tanks 20 may beeasily replaced.

The ink-jet heads 5 are arranged so as to form a small space between thelower surface of each ink-jet head 5 and the supporting surface 16 ofthe platen 12, and when an image is printed on the T-shirt 100, a partto be subjected to printing of the T-shirt 100 set to the platen 12 isconveyed to the space. With this configuration, by ejecting a colorink(s) from many ejection nozzles each having a small diameter, arrangedin the bottom surfaces of the ink-jet heads 5 in sequence, whilereciprocating the ink-jet heads 5 by the carriage 4, a desired colorimage may be printed on the T-shirt 100.

The printing control apparatus 70 shown in FIG. 2 is, for example,configured using a general purpose personal computer (PC) and includes amain body 71, a display as a display section 72, a keyboard 73 and amouse (pointing device) 74 as an operation section 75.

FIG. 5 is a block diagram showing a configuration of the printingcontrol apparatus 70 shown in FIG. 7. The printing control apparatus 70includes a CPU (Central Processing Unit) 81, a ROM (Read Only Memory)82, a RAM (Random Access Memory) 83, a HD (Hard Disk) 84, an operationsection 75, a display section 72, and an interface (I/F) 85, and theyare connected via a bus. The CPU 81, the ROM 82, the RAM 83, and the HD84 are incorporated into the main body 71 of the printing controlapparatus 70, and the operation section 75 is configured by the keyboard73 and the mouse 74.

The HD 84 stores various programs for use in control of operation of theprinting control apparatus 70. The HD 84 further stores various imagedata produced by software and various data according to the kind offabric such as a T-shirt. The CPU 81 performs various operations andprocesses on the basis of signals input with the operation section 75and various programs and data stored in the ROM 82, the RAM 83, and theHD 84. Then, data and the like are sent to the ink-jet printer 1 via theinterface 85. The RAM 83 is a volatile storage device which is readableand writable and stores results of the various operations and the likeobtained in the CPU 81. The interface 85 is connected to an interface ofthe ink-jet printer 1 and allows the printing control apparatus 70 andthe ink-jet printer 1 to communicate with each other.

FIG. 6 is a functional block diagram of the printing control apparatus70. As shown in FIG. 6, the printing control apparatus 70 includes animage data acquisition section 90 and an image data storage section 91.In the present example, the image data acquisition section 90 isrealized by the CPU 81, and the image data storage section 91 iscomposed of the RAM 83 and the HD 84.

The image data acquisition section 90 has a known function for use inproduction of image data and produces various image data on the basis ofsignals input from the keyboard 73 or the mouse 74 by an operator. Theimage data storage section 91 stores image data collected from removablestorage media such as a CD-ROM, an FD, and an MO and the Internet andimage data acquired by the image data acquisition section 90.

A desired image is printed on a T-shirt 100 using the ink-jet recordingapparatus of the present example as follows, for example. First, animage data which is desired to be printed on a T-shirt 100 is acquiredusing a keyboard 73 and a mouse 74 of a PC. In the acquisition of theimage data, image data is produced using software installed in the PC,or image data previously stored in a HD 84 is selected.

Then, the T-shirt 100 is fixed on the platen 12. That is, the T-shirt100 is overlaid on the platen 12 from the hem of the T-shirt 100 and isfixed with a fixing frame 15 along a supporting surface 16 of the platen12 without creases.

Subsequently, when the operator instructs that printing is performed,the image data is sent to the ink-jet printer 1 via the interface 85, anink(s) are ejected from ink-jet heads 5 on the basis of the image data,and the T-shirt 100 fixed on the platen 12 is subjected to printing.

The ink-jet recording apparatus may further comprise a heating unit. Theheating unit may be any unit as long as a heat-fixing step describedbelow is performed in the ink-jet recording apparatus. The heating unitis, for example, a unit of heating and pressurizing a printing-subjectedpart of the fabric, such as a hot press unit or the like. The ink-jetrecording apparatus may further comprise a pressurizing unit in additionto the heating unit. Any of the heating and the pressurizing may beperformed in advance, or both of them may be performed simultaneously.As described below, the heat-fixing step may be performed by anapparatus having a heating unit and a pressuring unit, different fromthe ink-jet recording apparatus.

The ink-jet recording apparatus may not include an ink tank for a whiteink and an ink-jet head for a white ink. In the method for forming animage, an image is printed on fabric after subjecting the fabric todischarge printing. Thus, a color image may be formed on deep-colorfabric without forming a base layer of a white ink.

In the present example, the image printing step is performed by theink-jet method. However, the image printing step may be performed byscreen printing, gravure printing, stencil, or the like using aconventionally known device or unit.

The method for forming an image may comprise a heat-fixing step ofheat-fixing the ink(s) on the fabric by subjecting theprinting-subjected part of the fabric to a heat treatment after theimage printing step. The heat-fixing step may be performed with the samedevice under the same conditions as in the heating step of the methodfor discharge printing. The heat-fixing step may be performed using adevice described in JP 2009-209493 A. According to this device, thefabric may be heated at 180° C. and pressurized.

The method for stabilizing a discharge printing agent is describedbelow. The method for stabilizing a discharge printing agent is a methodfor stabilizing a discharge printing agent that comprises thioureadioxide, the method comprising adding at least one of the followingcomponents (i) and (ii) to the discharge printing agent, (i) at leastone salt selected from the group consisting of a salt of monocarboxylicacid, a salt of ascorbic acid, and a salt of metasilicic acid, (ii)β-diketone. In the method for stabilizing a discharge printing agent,conditions such as the kind of at least one of the components (i) and(ii) and the amount of at least one of the component (i) and (ii) to beadded may be the same as those in the above-mentioned discharge printingagent.

EXAMPLES

The examples are described below together with comparative examples. Thepresent invention, however, is not limited by the following examples andcomparative examples.

Examples 1-1 to 1-17 and Comparative Examples 1-1 to 1-10

Examples 1-1 to 1-17 and Comparative Examples 1-1 to 1-10 are examplesof a discharge printing agent containing the thiourea dioxide and thecomponent (i). Components in each discharge printing agent composition(Table 1 or 2) except the thiourea dioxide and each salt were mixed, andthe thiourea dioxide and each salt were then added to the resultantmixture. Thus, discharge printing agents of Examples 1-1 to 1-17 andComparative Examples 1-1 to 1-10 were obtained.

Storing stability of each of the discharge printing agents of Examples1-1 to 1-17 and Comparative Examples 1-1 to 1-10 was evaluated by thefollowing method. That is, first, each of the discharge printing agentsof Examples 1-1 to 1-17 and Comparative Examples 1-1 to 1-10 as ofimmediately after preparation. 24 hours from preparation, 72 hours frompreparation was sprayed, by a spray method, seven times on each T-shirt(manufactured by Hanes, trade name: BEEFY (black)) on which a sheetobtained by cutting out 5 cm×5 cm had been placed within 1 hour beforethe spraying. Then, a discharge printing agent-applied part was heatedwhile moving an iron in the state of placing a Teflon (registeredtrademark) having a flat surface on the applied part. Subsequently, theT-shirt was washed with a washing machine as per normal (using adetergent) and was thereafter natural-dried in the shade. The degree ofdischarge printing of the T-shirt was evaluated according to thefollowing evaluation criteria using a discharge printing agentcontaining no salt as of immediately after preparation as a reference.

Storage Stability Evaluation of Discharge Printing Agent EvaluationCriteria:

-   AA: Color was discharged further significantly than the reference,-   A: Color was further discharged than the reference,-   B: Color was further discharged than the reference, and however,    discoloration was observed,-   C: The degree of color discharge was equal to or less than the    reference.

The composition and the evaluation result of each of the dischargeprinting agents of Examples 1-1 to 1-17 are summarized in Table 1. Thecomposition and the evaluation result of each of the discharge printingagents of Comparative Examples 1-1 to 1-10 are summarized in Table 2.

TABLE 1 Examples 1-1 1-2 1-3 1-4 1-5 1-6 1-7 1-8 1-9 Discharge Thioureadioxide 0.032 0.032 0.032 0.032 0.032 0.032 0.032 0.032 0.032 printingSodium formate 0.027 0.054 0.136 0.272 — — — — — agent Potassium formate— — — — 0.034 0.067 — — — composition Sodium acetate — — — — — — 0.0330.066 0.328 (g) Potassium acetate — — — — — — — — — Sodium butyrate — —— — — — — — — Sodium chloroacetate — — — — — — — — — Sodium glycolate —— — — — — — — — Sodium ascorbate — — — — — — — — — Sodium pivalate — — —— — — — — — Sodium metasilicate — — — — — — — — — Water 39.94 39.9139.83 39.70 39.93 39.90 39.94 39.90 39.64 Evaluation Immediately afterAA AA AA AA AA AA AA AA AA preparation 24 hours from A AA AA AA AA AA AA AA preparation 72 hours from A A AA AA A A B A AA preparation Examples1-10 1-11 1-12 1-13 1-14 1-15 1-16 1-17 Discharge Thiourea dioxide 0.0320.032 0.032 0.032 0.032 0.032 0.032 0.032 printing Sodium formate — — —— — — — — agent Potassium formate — — — — — — — — composition Sodiumacetate — — — — — — — — (g) Potassium acetate 0.039 0.079 — — — — — —Sodium butyrate — — 0.440 — — — — — Sodium chloroacetate — — — 0.466 — —— — Sodium glycolate — — — — 0.392 — — — Sodium ascorbate — — — — —0.792 — — Sodium pivalate — — — — — — 0.568 — Sodium metasilicate — — —— — — — 0.488 Water 39.93 39.89 39.53 39.50 39.58 39.18 39.40 39.48Evaluation Immediately after AA AA AA A A B A A preparation 24 hoursfrom A AA AA A A B A B preparation 72 hours from B A AA A A B A Apreparation

TABLE 2 Comparative Examples 1 1-1 1-2 1-3 1-4 1-5 1-6 1-7 1-8 1-9 1-10Discharge Thiourea dioxide 0.032 0.032 0.032 0.032 0.032 0.032 0.0320.032 0.032 0.032 printing L-arginine — 0.070 — — — — — — — — agentCupferron — — 0.621 — — — — — — — composition p-toluidine — — — 0.429 —— — — — — (g) Imidazole — — — — 0.272 — — — — — Sodium hydroxide — — — —— 0.016 — — — — Potassium hydroxide — — — — — — 0.022 — — — Sodiumchloride — — — — — — — 0.234 — — Sodium sulfate — — — — — — — — 0.568 —Sodium oxalate — — — — — — — — — 0.664 Water 39.97 39.90 39.35 39.5439.70 39.95 39.95 39.73 39.40 39.93 Evaluation Immediately after *1 C CC A C C C C C preparation 24 hours from C C C C A C C C C C preparation72 hours from C C C C C C C — — C preparation *1: Reference

As summarized in Table 1, in each of the discharge printing agents ofExamples 1-1 to 1-17, color as of 72 hours from preparation was furtherdischarged than the reference. In contrast, as summarized in Table 2, inthe discharge printing agent of Comparative Example 1-1 using notspecific salt, color discharge as of 24 hours from preparation was equalto or less than the reference, and even in each of the dischargeprinting agents of Comparative Examples 1-2 to 1-10 using compoundsother than the specific salts, such as amino acids as substitute for thespecific salts, color discharge as of immediately after preparation, 72hours from preparation was equal to or less than the reference. Asmentioned above, in discharge printing using thiourea dioxide, areaction intermediate is stabilized by a nucleophilic action of carbonylcarbon, resulting in increasing a yield of effective sulfoxylic acid.Thus, it was assumed that an effect of discharge printing wasconsequently increased.

Examples 1-18 to 1-27

Examples 1-18 to 1-27 also are examples of a discharge printing agentcontaining the thiourea dioxide and the component (i). Components ineach discharge printing agent composition (Table 3) except the thioureadioxide and each salt were mixed, and the thiourea dioxide and each saltwere then added to the resultant mixture. Thus, discharge printingagents of Examples 1-18 to 1-27 were obtained.

Storing stability of each of the discharge printing agents of Example1-18 to 1-27 was evaluated by the following method. That is, first, eachof the discharge printing agents of Example 1-18 to 1-27 as ofimmediately after preparation, 2 days from preparation, 7 days frompreparation, 14 days from preparation was sprayed, by a spray method,seven times on each T-shirt (manufactured by Hanes, trade name: BEEFY(black)) on which a sheet obtained by cutting out 5 cm×5 cm had beenplaced within 1 hour before the spraying. Then, a discharge printingagent-applied part was heated while moving an iron in the state ofplacing a Teflon (registered trademark) having a flat surface on theapplied part. Subsequently, the T-shirt was washed with a washingmachine as per normal (using a detergent) and was thereafternatural-dried in the shade. The degree of discharge printing of theT-shirt was evaluated based on the optical density (OD value) measuredusing a spectrophotometry: SpectroEye (light source: D65/10)manufactured by X-Rite. A reduction in OD value represents colordischarge. The OD value of a T-shirt before discharge printing was 1.7.

The composition and the evaluation result of each of the dischargeprinting agents of Examples 1-18 to 1-27 are summarized in Table 3.

TABLE 3 Examples 1-18 1-19 1-20 1-21 1-22 1-23 1-24 1-25 1-26 1-27Discharge Thiourea dioxide 0.5 0.5 0.5 1 1 1 2 2 2 1 printing Sodiumformate 0.5 1 2 0.5 1 2 0.5 1 2 — agent Sodium glycolate — — — — — — — —— 1 composition Gly 20 20 20 20 20 20 20 20 20 20 Lauryl betaine (*2) 11 1 1 1 1 1 1 1 1 PVA500 (*3) 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5Water Balance Balance Balance Balance Balance Balance Balance BalanceBalance Balance Evaluation Immediately after 0.999 0.979 0.879 0.7840.700 0.567 0.470 0.391 0.459 0.911 preparation 2 days from 1.266 1.2871.051 0.992 0.810 0.822 0.638 0.558 0.501 1.359 preparation 7 days from1.417 1.333 1.103 1.277 1.140 0.950 1.106 0.984 0.614 1.486 preparation14 days from 1.454 1.312 1.243 1.282 1.167 0.951 1.180 1.049 0.647 1.553preparation (*2): Surfactant (*3): Viscosity modifier; polyvinyl alcoholwith a molecular weight of 500 The unit of discharge printing agentcomposition: wt %

As summarized in Table 3, in each of discharge printing agents ofExamples 1-18 to 1-27 using Gly as a high boiling point solvent, areduction in OD value as of 14 days from preparation from 1.7 beforedischarge printing was 0.1 or more, and color was discharged to theextent that the different in color is observed by visual check.

Examples 2-1 to 2-7

Examples 2-1 to 2-7 are examples of a discharge printing agentcontaining the thiourea dioxide and the component (ii). Components ineach discharge printing agent composition (Table 1) except the thioureadioxide and the β-diketone were mixed, and the thiourea dioxide and theβ-diketone were then added to the resultant mixture. Thus, dischargeprinting agents of Examples 2-1 to 2-7 were obtained.

Storing stability of each of the discharge printing agents of Examples2-1 to 2-7 was evaluated in the same manner as in Examples 1-18 to 1-27.

The composition and the evaluation result of each of the dischargeprinting agents of Example 2-1 to 2-7 are summarized in Table 4.

TABLE 4 Examples 2-1 2-2 2-3 2-4 2-5 2-6 2-7 Discharge Thiourea dioxide5 5 5 5 5 5 5 printing Acetylacetone 1 2 5 10 — — — agent 3-acetyl-γ- —— — — 5 — — composition butyrolactone Dehydroacetic acid — — — — — 5 —Methyl acetoacetate — — — — — — 5 Diethanolamine 5 5 5 5 5 5 5 WaterBalance Balance Balance Balance Balance Balance Balance EvaluationImmediately after 0.397 0.569 0.701 0.511 0.514 0.358 0.400 preparation2 days from 0.550 0.540 0.599 0.632 0.658 0.462 0.385 preparation 7 daysfrom 0.598 0.688 0.698 0.753 0.740 0.561 0.485 preparation 14 days from0.782 0.781 0.658 0.705 0.873 0.755 0.633 preparation The unit ofdischarge printing agent composition: wt %

As summarized in Table 4, in each of discharge printing agents ofExamples 2-1 to 2-7, the OD value as of 14 days from preparation wassubstantially reduced from 1.7 before discharge printing, and color wasdischarged significantly. As mentioned above, in discharge printingusing thiourea dioxide, a reaction intermediate is stabilized by anucleophilic action of carbonyl carbon, and the intermediate isdecomposed over time. Therefore, the residence time of effectivesulfoxylic acid becomes long. Thus, it was assumed that an effect ofdischarge printing was consequently increased.

Examples 2-8 to 2-10 and Comparative Examples 2-1 to 2-2

Examples 2-8 to 2-10 and Comparative Examples 2-1 to 2-2 also areexamples of a discharge printing agent containing the thiourea dioxideand the component (ii). Components in each discharge printing agentcomposition (Table 5) except the thiourea dioxide and the β-diketone(2-hydroxy-2-methyl-4-pentanone in Comparative Example 2-2) were mixed,and thiourea dioxide and β-diketone were then added to the resultantmixture. Thus, discharge printing agents of Examples 2-8 to 2-10 andComparative Examples 2-1 to 2-2 were obtained.

Storing stability of each of the discharge printing agents of Examples2-8 to 2-10 and Comparative Examples 2-1 to 2-2 was evaluated in thesame manner as in Examples 1-18 to 1-27 except that the OD value as of28 days from preparation was measured as substitute for the OD value asof 2 days from preparation.

The composition and the evaluation result of each of the dischargeprinting agents of Examples 2-8 to 2-10 and Comparative Examples 2-1 to2-2 are summarized in Table 5.

TABLE 5 Examples Comparative Examples 2-8 2-9 2-10 2-1 2-2 DischargeThiourea dioxide 5 5 5 5 5 printing Acetylacetone 2 5 10 — — agent2-hydroxy-2-methyl- — — — — 5 composition 4-pentanone Gly 10 10 10 10 10Lauryl betaine (*2) 0.5 0.5 0.5 0.5 0.5 PVA500 (*3) 2 2 2 2 2Diethanolamaine 4.8 4.8 4.8 4.8 4.8 Water Balance Balance BalanceBalance Balance Evaluation Immediately after 0.580 0.764 0.653 0.4250.551 preparation 7 days from 0.497 0.475 0.749 0.761 1.469 preparation14 days from 0.794 0.522 0.872 0.849 3.599 preparation 28 days from0.870 0.545 0.630 1.307 1.709 preparation (*2): Surfactant (*3):Viscosity modifier; polyvinyl alcohol with a molecular weight of 500 Theunit of discharge printing agent composition: wt %

As summarized in Table 5, in each of the discharge printing agents ofExamples 2-8 to 2-10, the OD value as of 28 days from preparation wassignificantly reduced from 1.7 before discharge printing, and color wasdischarged significantly. In contrast, in each of the discharge printingagent of Comparative Example 2-1 using no β-diketone and the dischargeprinting agent of Comparative Example 2-2 using2-hydroxy-2-methyl-4-pentanone as substitute for β-diketone, the ODvalue as of 28 days from preparation was close to 1.7 before dischargeprinting.

Examples 3-1 to 3-3

Examples 3-1 to 3-3 are examples of a discharge printing agentcontaining the thiourea dioxide and the components (i) and (ii).Components in each discharge printing agent composition (Table 6) exceptthe thiourea dioxide, sodium formate, and acetylacetone were mixed, andthe thiourea dioxide, the sodium formate, and the acetylacetone wereadded to the resultant mixture. Thus, discharge printing agents ofExamples 3-1 to 3-3 were obtained.

Storing stability of each of the discharge printing agents of Examples3-1 to -3—was evaluated in the same manner as in Examples 1-18 to 1-27.

The composition and the evaluation result of each of the dischargeprinting agents of Examples 3-1 to 3-3 were summarized in Table 6.

TABLE 6 Examples 3-1 3-2 3-3 Discharge Thiourea dioxide 5 5 5 printingagent Sodium formate 5 5 5 composition Acetylacetone 5 10 15 Gly 20 2020 Lauryl betaine (*1) 1 1 1 PVA500 (*2) 0.5 0.5 0.5 Water BalanceBalance Balance Evaluation Immediately after 0.289 0.273 0.283preparation  2 days from preparation 0.263 0.267 0.262  7 days frompreparation 0.313 0.294 0.301 14 days from preparation 0.377 0.361 0.314(*2): Surfactant *3: Viscosity modifier; polyvinyl alcohol with amolecular weight of 500 The unit of discharge printing agentcomposition: wt %

As summarized in Table 6, in each of the discharge printing agents ofExamples 3-1 to 3-3, the OD value as of 14 days from preparation wassignificantly reduced from 1.7 before discharge printing, and color wasdischarged significantly. As mentioned above, in discharge printingusing thiourea dioxide, a reaction intermediate is stabilized by anucleophilic action of carbonyl carbon, and the intermediate isdecomposed over time. Therefore, a yield of effective sulfoxylic acid isincreased, and the residence time of effective sulfoxylic acid becomeslong. Thus, it was assumed that an effect of discharge printing wasconsequently increased.

Examples 4-1 to 4-3

Examples 4-1 to 4-3 are examples of a discharge printing agentcontaining thiourea dioxide, β-diketone (the component (ii)), and anamine base (the component (iii)). In Example 4-2, the discharge printingagent further contains β-diketone. In Example 4-3, the dischargeprinting agent further contains ketone. Thiourea dioxide, disodiummalonate (the component (i)), and2-amino-2-hydroxymethyl-1,3-propanediol (AHP, an amine base (thecomponent (iii)) shown in each discharge printing agent composition(Table 7) were completely dissolved in water. Thereafter, as summarizedin Table 7, N-methyl acetoacetic acid amide was added in Example 4-2,and 2-hydroxy-2-methyl-4-pentanone was added in Example 4-3. Thus,discharge printing agents of Examples 4-1 to 4-3 were obtained.

Storing stability of each of the discharge printing agents of Examples4-1 to 4-3 was evaluated by the following method. That is, first, eachof the discharge printing agents of Examples 4-1 to 4-3 as ofimmediately after the preparation, 0.5 months from preparation, 1 monthfrom preparation, 2 months from preparation, 3 months from preparationwas sprayed, by a spray method, seven times on each T-shirt(manufactured by Hanes, trade name: BEEFY (black)) on which a sheetobtained by cutting out 5 cm×5 cm had been placed within 1 hour beforethe spraying. Then, a discharge printing agent-applied part was heatedwhile moving an iron in the state of placing a Teflon (registeredtrademark) having a flat surface on the applied part. Subsequently, theT-shirt was washed with a washing machine as per normal (using adetergent) and was thereafter natural-dried in the shade. The degree ofdischarge printing of the T-shirt was evaluated based on the opticaldensity (OD value) measured using a spectrophotometry: SpectroEye (lightsource: D65/10) manufactured by X-Rite. A reduction in OD valuerepresents color discharge. The OD value of a T-shirt before dischargeprinting was 1.7.

The composition and the evaluation result of each of the dischargeprinting agents of Examples 4-1 to 4-3 are summarized in Table 7.

TABLE 7 Examples 4-1 4-2 4-3 Discharge Thiourea dioxid (TD) 5 5 5printing Disodium malonate 5 5 5 agent 2-amino-2-hydroxymethyl- 10 10 10composition 1,3-propanol (AHP) N-methyl acetoacetic acid — 10 — amide(NMAA) 2-hydroxy-2-methyl-4- — — 10 pentanone (HMP) Water BalanceBalance Balance Evaluation Immediately after preparation 0.334 0.3410.343 0.5 months from preparation 0.367 0.318 0.331 1.0 month frompreparation 0.376 0.353 0.405 2.0 months from preparation 0.548 0.4230.436 3.0 months from preparation — 0.457 0.555 The unit of dischargeprinting agent composition: wt %

As summarized in Table 7, in each of the discharge printing agents ofExamples 4-1 to 4-3, the OD value as of 2 months from preparation wassignificantly reduced from 1.7 before discharge printing, and color wasdischarged significantly. Specifically. Example 4-2 using N-methylacetoacetic acid amide as β-diketone showed the largest decrease in ODvalue, and the really low OD value was maintained after 3 months frompreparation.

It will be obvious to those having skill in the art that many changesmay be made in the above-described details of the particular aspectsdescribed herein without departing from the spirit or scope of theinvention as defined in the appended claims.

What is claimed is:
 1. A discharge printing agent comprising thioureadioxide, wherein the discharge printing agent further comprises at leastone of the following components (i) and (ii): (i) at least one saltselected from the group consisting of a salt of monocarboxylic acid, asalt of ascorbic acid, and a salt of metasilicic acid; and (ii)β-diketone.
 2. The discharge printing agent according to claim 1,wherein the salt of monocarboxylic acid is at least one of a salt offormic acid, a salt of aliphatic carboxylic acid, and a salt of analiphatic carboxylic acid derivative.
 3. The discharge printing agentaccording to claim 2, wherein the salt of aliphatic carboxylic acid isat least one of a salt of acetic acid and a salt of butyric acid.
 4. Thedischarge printing agent according to claim 1, wherein the β-diketone isat least one selected from the group consisting of acetylacetone,disodium malonate, 3-acetyl-γ-butyrolactone, dehydroacetic acid, methylacetoacetate, and N-methyl acetoacetic acid amide.
 5. The dischargeprinting agent according to claim 1, wherein the discharge printingagent comprises both of the components (i) and (ii).
 6. The dischargeprinting agent according to claim 1, wherein the discharge printingagent comprises at least one of the components (i) and (ii) and furthercomprises the following component (iii): (iii) an amine base.
 7. Thedischarge printing agent according to claim 6, wherein the component(iii) is a primary amine base.
 8. The discharge printing agent accordingto claim 7, wherein the component (iii) is2-amino-2-hydroxymethyl-1,3-propanediol (AHP).
 9. The discharge printingagent according to claim 1, wherein the amount of the thiourea dioxideto be added is 0.5 wt % to 5 wt % relative to the total amount of thedischarge printing agent, and the amount of at least one of thecomponents (i) and (ii) to be added is 1 wt % to 15 wt % relative to thetotal amount of the discharge printing agent.
 10. A container comprisinga discharge printing agent, wherein the discharge printing agent is thedischarge printing agent according to claim
 1. 11. The containeraccording to claim 10, wherein a main body of the container comprises acase.
 12. An ink-jet recording apparatus comprising a liquid ejectingunit of ejecting a liquid, wherein the apparatus further comprises aunit of applying a discharge printing agent, and the discharge printingagent is the discharge printing agent according to claim
 1. 13. A methodfor discharge printing of fabric, the method comprising: a dischargeprinting agent-applying step of applying a discharge printing agent tofabric; and a heating step of heating a discharge printing agent-appliedpart, wherein as the discharge printing agent, the discharge printingagent according to claim 1 is used.
 14. A method for forming an image onfabric, the method comprising: a discharge printing step of subjectingfabric to discharge printing; and an image printing step of printing animage on a discharge printing-subjected part with an ink, wherein thedischarge printing step is performed by the method according to claim13.
 15. The method according to claim 14, wherein the image printingstep is performed by an ink-jet method.
 16. A method for stabilizing adischarge printing agent that comprises thiourea dioxide, the methodcomprising adding at least one of the following components (i) and (ii)to the discharge printing agent, (i) at least one salt selected from thegroup consisting of a salt of monocarboxylic acid, a salt of ascorbicacid, and a salt of metasilicic acid, (ii) β-diketone.
 17. The methodaccording to claim 16, comprising adding both the components (i) and(ii) to the discharge printing agent.
 18. The method according to claim16, comprising adding at least one of the components (i) and (ii) to thedischarge printing agent and further comprising adding the followingcomponent (iii) to the discharge printing agent, (iii) an amine base.19. The method according to claim 18, wherein the component (iii) is2-amino-2-hydroxymethyl-1,3-propanediol (AHP).